title: Evaluation of a noninvasive method for monitoring percutaneous absorption of lidocaine in vivo.
abstract: The pharmacodynamic measurement of in vivo skin penetration of lidocaine was explored with an instrument used in dentistry to determine tooth pulp vitality. The instrument delivers a low-current, pulsatile electrical waveform of increasing intensity with time. The readings, which are reproducible, are in arbitrary units on a scale of 0-80. Testing of naive sites showed variation as a function of location, even over relatively small distances. The response at a marked site over a 12-hr period generally was consistent in five subjects. Following intradermal administration of 1 or 2% lidocaine hydrochloride injection in one subject, the instrument reached its maximum value within 2 min. This was followed by a sustained plateau and then a gradual falloff of the effect. Topical formulations containing 5% lidocaine base and corresponding blank formulations were applied under occlusion within Hilltop chambers to intact skin on the forearms of human volunteers for 3 hr. While the response to a 40% propylene glycol formulation was not significantly different from the corresponding control, a cream exhibited slow development of profound anesthesia that lasted for several hours following chamber removal.
authors.affiliation: Department of Pharmaceutics, Rutgers College of Pharmacy, Piscataway, New Jersey 08854.
authors.forename: G P
authors.initials: GP
authors.lastname: Kushla
authors.forename: J L
authors.initials: JL
authors.lastname: Zatz
mesh_terms: D000279:Administration, Cutaneous; D004558:Electric Stimulation; D006801:Humans; D007271:Injections, Intradermal; D008012:Lidocaine / Q000493:pharmacokinetics*; D008991:Monitoring, Physiologic / Q000379:methods; D009824:Ointments; D014677:Pharmaceutical Vehicles; D019946:Propylene Glycol; D011409:Propylene Glycols; D012869:Skin Absorption / Q000502:physiology*
chemical_list: D009824:Ointments; D014677:Pharmaceutical Vehicles; D011409:Propylene Glycols; D019946:Propylene Glycol; D008012:Lidocaine